The present disclosure relates to vibration compacting machines, and more particularly to an eccentric assembly for a vibration compacting machine.
Vibration compacting machines are used in leveling paved or unpaved ground surfaces. A typical vibration compacting machine includes an eccentric assembly, which is located inside a drum of a drum assembly of the compacting machine and, while being rotated by an electrical or hydraulic motor, the eccentric assembly generates vibrations due to its eccentricity. Then, the vibrations generated by the eccentric assembly are transferred to the drum assembly, thereby enhancing compacting efficiency of the compacting machine.
As such, eccentricity of an eccentric assembly is essential for generating vibrations through rotation thereof, and higher degree of eccentricity generates higher amplitude of vibration that is desirable when larger compacting power is required. However, eccentricity of an eccentric assembly is not desirable during starting of rotation of the eccentric assembly. During this start-up period, the vibrations generated by the eccentric assembly are not used productively by the vibration compacting machine because vibration compacting machines generally do not start their working pass during this period. Moreover, as eccentricity of the eccentric assembly requires higher start-up torque, which is significantly larger than the torque required for maintaining rotation of the eccentric assembly, a more powerful electrical or hydraulic motor is needed due to eccentricity during the start-up period. In brief, it can be said that eccentricity of an eccentric assembly during the start-up period is not just useless but also undesirable.
On the market, there are solutions that provide systems for controlling eccentricity or an eccentric moment of eccentric assemblies. Examples of such solutions are U.S. Pat. No. 7,270,025 B2, which discloses “Adjusting device for regulating the eccentric moment of a roller drum eccentric shaft”, and U.S. Pat. No. 6,585,450 B2 which discloses “Speed controlled eccentric assembly”.
However, it is still required to develop an eccentric assembly having a simple and economic structure that is configured such that during a start-up period of the eccentric assembly, the eccentric moment is zero or has a very small value, and then when the eccentric assembly has a sufficient rotational speed by the completion of start-up, sufficient eccentric moment in the eccentric assembly can be provided for working.
According to one aspect of the present disclosure, there is provided an eccentric assembly for a vibration compacting machine controlled by rotational speed thereof. The eccentric assembly includes: a housing driven and rotated by a motor, an eccentric shaft installed in the housing so as to have a changeable angular position by rotating relative to the housing; a locking device adopted to lock the eccentric shaft by engaging with one side of the eccentric shaft, and to unlock the eccentric shaft when a rotational speed of the housing is greater than a predetermined locking critical speed col; a clamping device adopted to clamp an opposite side of the one side of the eccentric shaft that engages with the locking device, and to release clamping to the eccentric shaft when a rotational speed of the housing is greater than a predetermined clamping critical speed coc; and a stopper installed in the housing so as to limit a rotation angle of the eccentric shaft generated when locking and clamping to the eccentric shaft are released.